Ignition issue

  • 3.6L
  • 6 CYL
  • 2WD
  • 51,000 MILES
Vehicle started to stutter/stumble one day while at highway speed. Put code reader on vehicle and got code P0305 (misfire in cylinder 5). Replaced spark plugs and no change to issue. Then swapped coil pack from cylinder 5 to 3. Now have codes P0305 and P0303 (misfire in both cylinders). Cleared codes and still have P0303. Assuming that the coil pack is bad. Just looking for some clarification I am on the right track here.


Do you
have the same problem?
Monday, September 14th, 2020 AT 2:21 PM

1 Reply

Hi Jason,

Yes, it sounds like you are on the right track! I had the exact same situation with a Toyota Sienna last week. If you want to double the coil pack that you now have on cylinder 3 (assuming you haven't moved it since you wrote this), there are a couple of things you can do. The easiest is to start the vehicle and while it is running, pull the coil pack off of cylinder 3. There should be no change in the engine sound if it is bad.
The second thing you can do only requires a test light. Start the vehicle, clip the alligator clip to a good ground, then pull the coil pack in question. Be sure to keep your fingers away from the end of the coil pack and the end of the test light!!! You can get quite a shock if you are careless. Bring the tip of the test light into the end of the coil pack boot and you should see a spark when the coil pack fires. If there is no spark, the coil pack is not working.
When you have a working coil pack in pace, the engine should run smoother. Don't worry about clearing the codes, they will reset in about a week, depending on how often the vehicle is driven.
I have included 2 links for your convenience. The first is a link to an article on How to Use a Test Light and the second is a video on how to use a test light.

Thanks for visiting 2CarPros! Best of luck to you!


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Monday, September 14th, 2020 AT 3:11 PM

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